1. Field of the Invention
The present invention relates to herbicides and more particularly to compositions and methods for selectively controlling weeds.
2. Description of the Prior Art
Weed control for agricultural purposes remains a topic of great importance even though many different classes of compounds as well as thousands of specific compounds have been disclosed in the literature for the purposes of both general and selective weed control. A high degree of herbicidal or weed controlling effectiveness is an important aim in weed control, and the problem of controlling weeds in agricultural and horticultural crop areas where both weeds and crop plants belong to similar families has not been solved satisfactorily. Possibly, no generally applicable approach to selectively controlling specific plants or weeds within a given crop is feasible and research aiming at new compounds and methods for selective weed control is being continued all over the world. Further, environmental problems such as residual components of agrochemical agents represent a problem of increasing importance and it is essential to find and use such weed control agents that are not harmful to animals and humans nor produce residual compounds that have such undesired effects.
German Published Patent Application No. 2,417,487 discloses that a class of compounds, i.e. the benzyl phenoxy alkanoic acids as well as derivatives thereof, is suitable for selective weed control purposes and such compounds show a remarkable degree of selective herbicidal or weed control effectiveness against undesired growth of the Graminae or grass-type(monocotyledonous) plants while being substantially inactive against dicotyledonous species.
A structurally related group of chemical compounds has been disclosed by us previously for therapeutic lipid lowering purposes, i.e. for reducing the colesterol or fat content of the blood, c.f. for example our German Published Patent Application No. 2,461,069. In accordance with the present invention we have found that a specific compound previously disclosed by us as a lipid lowering agent and its salts not previously disclosed have a surprisingly high degree of herbicidal effectiveness against both weeds of the monocotyledonous and dicotyledonous species. Specifically, it has been discovered that the 4-(4'-chlorobenzyl)-phenoxy acetic acid as well as the salts of said acid provide for the improved herbicidal effects just mentioned when used for selective weed control in pre-emergence and/or post-emergence type applications.